hardness: shift of negative value

These tasks contain shift of negative value (-1 << ...):

hardness-nfm22/hardness_fillercode_fillercodesize_normal_file-94.i
hardness-nfm22/hardness_fillercode_fillercodesize_ps-cn-100_file-94.i 
hardness-nfm22/hardness_fillercode_fillercodesize_ps-cn-10_file-94.i 
hardness-nfm22/hardness_fillercode_fillercodesize_ps-cn-25_file-94.i 
hardness-nfm22/hardness_operatoramount_amount50_file-94.i 
hardness-nfm22/hardness_loopvsstraightlinecode_50-while_file-94.i 
hardness-nfm22/hardness_loopvsstraightlinecode_50-1loop_file-94.i
hardness-nfm22/hardness_fillercode_fillercodestructure_normal_file-94.i
hardness-nfm22/hardness_fillercode_fillercodestructure_filler-ps-ci_file-94.i
hardness-nfm22/hardness_fillercode_fillercodestructure_filler-pr-ci_file-94.i
hardness-nfm22/hardness_fillercode_fillercodestructure_filler-pe-ci_file-94.i
hardness-nfm22/hardness_fillercode_fillercodestructure_filler-pe-co_file-94.i
hardness-nfm22/hardness_fillercode_fillercodestructure_filler-pe-cn_file-94.i
hardness-nfm22/hardness_fillercode_fillercodesize_ps-cn-50_file-94.i
hardness-nfm22/hardness_fillercode_fillercodestructure_filler-pr-cn_file-94.i
hardness-nfm22/hardness_fillercode_fillercodestructure_filler-pr-co_file-94.i
hardness-nfm22/hardness_fillercode_fillercodestructure_filler-ps-cn_file-94.i
hardness-nfm22/hardness_fillercode_fillercodestructure_filler-ps-co_file-94.i

Shift of negative signed integer is undefined behavior. From C11 standard, paragraph 6.5.7.4:

The result of E1 << E2 is [...]. If E1 has an unsigned type, [...]. If E1 has a signed type and nonnegative value, and E1 × 2^E2 is representable in the result type, then that is the resulting value; otherwise, the behavior is undefined.

(I can look also to other standards if C11 would not be applicable here).

witnesses.zip contains test harnesses that after compilation with -fsanitize=undefined show the error. There's also the script run.sh that automate this task and shows the problem in these benchmarks (adjust the SV_BENCHMARKS variable to point to sv-benchmarks).